Yieldable pit posts



4. T. BooP v YIELDABLE. PIT POSTS Filed March 27, 1962 Fig.2.

n E INVENTOR Y John Boop IO 7 I &'\\\ a United States Patent 3,133,720 YTELDABLE PIT POSTS John T. Boop, Youngstown, Ohio, assignor to Commercial Shearing & Stamping Co., Youngstown, Ohio Filed Mar. 27, 1962, Ser. No. 182,801 2 Claims. (Cl. 248-356) This invention relates to yieldable pit posts and particularly to a hydraulic pit post for use in mine and tunnel construction.

The use of temporary mine posts or supports has been practiced since the inception of underground mining. Historically, these temporary posts have been timber posts. These posts have been sawed to length and wedged in place. It was, of course, impossible to set wooden posts so that each post carried the same load. Moreover, wooden posts would fail in sequence as they became loaded. During roof settlement, the tightest post failed first, followed by the next tightest one as it became overloaded and so on in an increasing chain reaction. There was no redistribution of the load among the posts and no possibility of holding the roof in the area of failure.

The yieldable post of the present invention replaces these wooden posts and is designed to be installed so that all posts assume an original preloading which is equal. In the event of roof settlement, the posts yield before reaching their breaking point so as to redistribute the load over the posts in a given area.

I provide, in a preferred embodiment of my invention, a base, a piston on the base, a cylinder surrounding the piston and movable relatively therewith, an elongated reservoir, pump means between the reservoir and cylinder and relief means connecting the cylinder and reservoir to release fluid from the cylinder at a fixed preselected pressure. Preferably a check valve is provided between the reservoir and cylinder to permit manual raising or collapsing of the cylinder on the piston to set the post in the mine. In a preferred form of my invention the pump, relief valve and check valve are arranged in a cylindrical section between and separating the reservoir and cylinder.

In the foregoing general description I have set out certain objects, purposes and advantages of my invention. Other objects, purposes and advantages will be apparent from a consideration of the following description and the accompanying drawings in which:

FIGURE 1 is a side elevation partially in section of a preferred embodiment of my invention;

FIGURE 2 is a section on the line IIII of FIG- URE 1;

FIGURE 3 is a top plan view of the post of FIG- URE l; and

FIGURE 4 is a section on the line IVIV of FIG- URE 1.

Referring to the drawings 1 have illustrated a base member having a foot 111, a hollow base 11 and a head 12. A ram or piston 13 is removably fixed at one end to the head 12 by a bolt 14. The opposite end of piston 13 is provided with a head 15 carrying a sealing gasket assembly 16. A cylinder 17 surrounds piston 13 and is slidably in sealing contact with gasket assembly 16. A stop and spacer ring 18 is fixed to the open end 17a of cylinder 17 and is provided with a sealing gasket 19 to maintain the cylinder coaxially over the piston while providing the necessary stop to engage stop ring 20 on the exterior of piston 13.

A pump section 21 is attached to the cylinder 17 and forms the closure therefor. This pump section is provided with a spring loaded relief valve 22 communicating ice between the interior of cylinder 17 and a hollow cylindrical reservoir 23. A spring loaded release ball valve 24 is mounted in this pump section and is opened by a pin 25 actuated by a handle 26 pivoted on the exterior of the pump section. This release valve is for the purpose of permitting free flow between cylinder 17 and reservoir 23. A reciprocating pump piston 27 is movable in pump barrel 28 by a handle 29, pivoted on the pump member. A check valve 311 communicates between reservoir 23 and pump barrel 28. A second check valve 31 communicates between pump barrel 28 and cylinder 17.

The reservoir 23 is provided with a head 32 having a filler opening 33. A tubular vent 34 is provided at the end of the reservoir adjacent the head 32. This vent communicates between the interior of the reservoir and the atmosphere. A ring 35 is provided adjacent the head 32 through which a rope 36 may be passed for attachment to an eye 37 in handle 26.

A protective bumper 38 is preferably formed on the pump section 21 to protect pump handle 29 from dam age. A slidable keeper 39 having an opening 40 slidable on cylinder 17 and a spaced opening 41 receiving handle 29 may be provided for holding the handle in the closed position and at the same time providing a convenient carrying handle for transporting the post from place to place.

In operation the post is placed with foot 10 on the floor of the mine. Handle 26 is raised to open valve 24 and the pump section 21, cylinder 17 and reservoir are raised by hand until the head 32 reaches the mine roof. The handle 26 is next lowered to the position shown in FIGURE 1 and the pump handle 29 actuated to cause piston 27 to pump fluid from reservoir 23 through valve 30, barrel 28 and valve 31 into cylinder 17 above piston head 15 until a desired pressure is reached.

If, during the mine operation, roof settlement occurs and the post is overloaded, fluid flows from cylinder 17 through relief valve 22 into reservoir 23 until the load is uniformly reestablished on all posts in the area.

When mining operations have ceased and it is desired to pull the posts, a rope 36 is attached to ring 37 or handle 26 and passed through ring 35. A pull on the rope opens valve 24 releasing fluid from cylinder 17 into reservoir 23 and upsetting the post which is then pulled endwise out of the area under release.

While I have illustrated a presently preferred embodiment of my invention it will be understood that my invention may be otherwise embodided within the scope of the following claims:

I claim:

1. A yieldable pit prop comprising an elongated cylindrical reservoir, a head on one end of said reservoir, a pump section coaxial with and fitting onto the opposite end of said reservoir, pump means in said pump section, lever means pivoted 0n the pump section for driving said pump means, an elongated cylinder on the pump section opposite the reservoir and coaxial therewith, ram means in the cylinder movable out of said cylinder by fluid delivered from the reservoir into the cylinder, 21 base on said ram, a first passage in said pump section parallel to the cylinder axis communicating at one end with the cylinder and closed at the opposite end, a second passage in the pump section parallel to the first passage and spaced therefrom communicating at one end with the reservoir and closed at the opposite end, relief valve means in the pump section communicating between the first and second passage releasing fluid from the cylinder to the reservoir at preselected pressure and a connection between the first passage and second passage in the pump section, a spring loaded ball valve in said connection normally preventing fluid flow therethrough, a pin movable in the pump section transverse to the cylinder axis to move the ball from said connection to permit communication between said passages and handle means pivoted on the pump section for selectively actuating said pin and thereby said ball.

2. A prop as claimed in claim 1 having a keeper slidable on the reservoir, said keeper having an opening releasably receiving the lever means spaced from the pivot whereby a carrying handle is formed and a ring means 10 adjacent one end slidably receiving a flexible release cable attached to the handle means pivoted on the pump whereby tension applied to the cable releases the ball.

References Cited in the file of this patent UNITED STATES PATENTS Reischer et a1. June 28, 1955 Tebb et a1. May 23, 1961 FOREIGN PATENTS Great Britain July 28, 1941 Great Britain Dec. 12, 1956 Great Britain Sept. 14, 1960 Germany Mar. 22, 1962 

1. A YIELDABLE PIT PROP COMPRISING AN ELONGATED CYLINDRICAL RESERVOIR, A HEAD ON ONE END OF SAID RESERVOIR, A PUMP SECTION COAXIAL WITH AND FITTING ONTO THE OPPOSITE END OF SAID RESERVOIR, PUMP MEANS IN SAID PUMP SECTION, LEVER MEANS PIVOTED ON THE PUMP SECTION FOR DRIVING SAID PUMP MEANS, AN ELONGATED CYLINDER ON THE PUMP SECTION OPPOSITE THE RESERVOIR AND COAXIAL THEREWITH, RAM MEANS IN THE CYLINDER MOVABLE OUT OF SAID CYLINDER BY FLUID DELIVERED FROM THE RESERVOIR INTO THE CYLINDER, A BASE ON SAID RAM, A FIRST PASSAGE IN SAID PUMP SECTION PARALLEL TO THE CYLINDER AXIS COMMUNICATING AT ONE END WITH THE CYLINDER AND CLOSED AT THE OPPOSITE END, A SECOND PASSAGE IN THE PUMP SECTION PARALLEL TO THE FIRST PASSAGE AND SPACED THEREFROM COMMUNICATING AT ONE END WITH THE RESERVOIR AND CLOSED AT THE OPPOSITE END, RELIEF 